Barter without direct contact between the traders. Individuals from one group leave trade goods at a neutral location on the edge of their territory and then leave. Sometime later, members of the other community pick up the goods and leave something in exchange. The first group then returns and either picks up the things that were left by the strangers or leaves them until additions or substitutions are made that are acceptable. In the past, dumb-barter of this sort occurred in parts of west africa, northern scandinavia, india, sri lanka, sumatra, timor, new guinea, and the amazon basin of south america. Dumb barter is also known as "silent trade" and "depot trade. "